CFD-DEM modelling of dense gas-solid reacting flow: Recent advances and challenges

Dense gas-solid reacting flow involves multiphase flow, heat and mass transfer, and chemical reactions. The computational fluid dynamics-discrete element method (CFD-DEM) has emerged as a promising tool for investigating and optimizing dense gas-solid reacting systems at the particle scale. Despite the rapid advancement of CFD-DEM and its successful application to various chemical engineering processes, there is still a lack of a comprehensive review of the theory and applications of CFD-DEM modelling of dense gas-solid reacting flow. This article aims to bridge this gap by providing a systematic review of recent progress in the development of CFD-DEM models and their applications to dense gas-solid reacting systems. This article begins by providing a comprehensive review of sub-models used to describe flow dynamics and thermochemical conversion in dense gas-solid reacting systems. The numerical algorithms and implementations, ranging from flow to heat and mass transfer, as well as speed-up methods, are examined in detail. The focus then shifts to the recent advancements of CFD-DEM applications in chemical engineering processes related to dense gas-solid reacting systems. Specific areas of interest include the thermochemical conversion of biomass and coal, blast furnace ironmaking, chemical looping combustion, solid waste incineration, lime shaft kiln calcination, and more. Furthermore, the challenges associated with effectively and efficiently modelling dense gas-solid reacting flow, particularly about the multi- physics and multi-scale characteristics in both time and space, are thoroughly assessed. By addressing these challenges, this review is expected to foster further progress in the field and enhance our understanding and control of dense gas-solid reacting systems in various applications.